TWI797992B - Method for manufacturing vanadium electrolyte - Google Patents

Abstract

A method for manufacturing a vanadium electrolyte is used to solve the problem of high manufacturing cost of the conventional vanadium electrolyte. The method for manufacturing the vanadium electrolyte includes mixing an aqueous vanadate solution and a first aqueous sulfuric acid solution to form a mixing slurry including a dioxovanadium(V) cation (VO₂ ⁺) and a sulfate anion (SO₄ ^2-). The mixing slurry is constant current electrolyzed to reduce the dioxovanadium(V) cation, forming a vanadyl(IV) anion (VO²⁺). The vanadyl(IV) anion and the sulfate anion can thus form vanadyl(IV) sulfate (VOSO₄), forming an aqueous vanadyl(IV) sulfate solution. An alkali solution is added to the aqueous vanadyl(IV) sulfate solution to form vanadium(IV) oxydihydroxide (VO(OH)₂) that is not water soluble. The vanadium(IV) oxydihydroxide is filtered and then dissolved in a second aqueous sulfuric acid solution to obtain the vanadium electrolyte.

Description

Preparation method of vanadium electrolyte

The invention relates to a method for preparing an electrolyte, in particular to a method for preparing a vanadium electrolyte.

Vanadium redox battery (VFB), also known as vanadium redox flow battery (VRFB), is a possibility to use vanadium ions in different oxidation states to store chemical potential energy. Rechargeable flow batteries, vanadium flow batteries are very suitable for large-scale power storage applications due to their extremely large energy capacity.

Vanadium redox flow battery uses vanadium electrolyte as electrolyte. Therefore, the performance of vanadium electrolyte is very important for the development of vanadium redox flow battery. For example, Chinese Patent Publication No. 102110837 discloses a method for preparing a conventional vanadium electrolyte. In this conventional preparation method, vanadium pentoxide (V ₂ O ₅ ) is used as a raw material, and concentrated sulfuric acid The solution (aqueous sulfuric acid solution with a concentration of 98%) dissolves vanadium pentoxide at high temperature, and then electrolyzes to form vanadyl sulfate, and further prepares to form the conventional vanadium electrolyte. However, the conventional method for preparing vanadium electrolyte uses expensive vanadium pentoxide as a raw material (about 4,000 yuan per kilogram), and dissolving vanadium pentoxide with the concentrated sulfuric acid solution at high temperature not only has considerable risks , also has relatively high requirements on the preparation equipment, thus increasing the preparation cost of the conventional vanadium electrolyte.

In view of this, the preparation method of known vanadium electrolyte really still needs to be improved. want.

In order to solve the above problems, the purpose of this invention is to provide a preparation method of vanadium electrolyte, which uses cheap vanadium-containing compounds as raw materials.

The preparation method of the vanadium electrolyte solution of the present invention comprises: mixing a vanadate aqueous solution and a first sulfuric acid aqueous solution (for example, including 50-60% sulfuric acid and 40-50% water in weight percent), to obtain a Mixed slurry, the vanadate aqueous solution is 25 ~ 50g/L sodium vanadate aqueous solution, the mixed slurry contains a dioxyvanadyl ion-sulfate ion; the mixed slurry is subjected to constant current electrolysis, so that the double The vanadyl ion is reduced to form a vanadyl ion, and together with the sulfate ion, vanadyl sulfate is formed to form a vanadyl sulfate aqueous solution; a lye (for example, a hydroxide Sodium aqueous solution, an ammonia solution or a potassium hydroxide aqueous solution), so that vanadyl sulfate forms vanadyl hydroxide insoluble in water; and the vanadyl hydroxide obtained by filtering is dissolved in a second sulfuric acid aqueous solution to obtain a vanadium electrolytic liquid.

Accordingly, the preparation method of the vanadium electrolyte of the present invention can reduce the trivalent vanadium ions (VO ₂ ⁺ ) in the mixed slurry to form tetravalent vanadium ions (VO ²⁺ ), and make the The vanadium sulfate can be separated from sulfates such as sodium sulfate, ammonium sulfate or potassium sulfate to obtain the vanadium electrolyte. Moreover, workers can choose low-cost vanadate as a raw material, and after reacting with the first sulfuric acid aqueous solution, they can obtain trivalent vanadium ions (VO ₂ ⁺ ) capable of constant current electrolysis, and then prepare the The vanadium electrolyte can achieve the effect of reducing the manufacturing cost of the vanadium electrolyte.

The preparation method of the vanadium electrolyte solution of the present invention, wherein, the mixed slurry can comprise the vanadate aqueous solution of 30-70% and the first sulfuric acid aqueous solution of 30-70% in volume percentage, and the mixed slurry is relatively Preferably, it may contain 30-50% of the vanadate aqueous solution and 50-70% of the first sulfuric acid aqueous solution in terms of volume percentage. In this way, the electrolysis efficiency of the subsequent constant current electrolysis can be improved to increase the proportion of tetravalent vanadium ions (VO ²⁺ ) in the obtained vanadyl sulfate aqueous solution.

The preparation method of the vanadium electrolyte solution of the present invention puts the mixed slurry into an electrolytic tank for constant current electrolysis, wherein, an anode electrode and a cathode electrode are arranged in the electrolytic tank, and the anode electrode can be a titanium plated An iridium electrode or a rhodium-plated titanium electrode, and the cathode electrode can be a lead electrode or a graphite electrode. In this way, the electrodes will not participate in the electrolysis reaction, and will not be dissolved by the mixed slurry to generate impurities.

In the preparation method of the vanadium electrolyte of the present invention, the constant current electrolysis can be carried out with a current of 10 to 20A for 2 to 8 hours to form the vanadyl sulfate aqueous solution, preferably the constant current electrolysis can be carried out with a current of 15 to 20A for 4 ~8 hours. In this way, the vanadyl ions in the mixed slurry can be reduced to form vanadyl ions.

The preparation method of the vanadium electrolyte solution of the present invention, wherein, the alkaline solution is added to the vanadyl sulfate aqueous solution to adjust the pH value of the mixed solution comprising the vanadyl sulfate aqueous solution and the alkaline solution to 4~6, so that The vanadyl sulfate forms vanadyl hydroxide, preferably the pH value of the mixed solution comprising the vanadyl sulfate aqueous solution and the lye can be adjusted to 5. In this way, vanadyl sulfate can be effectively promoted to form water-insoluble vanadyl hydroxide, and then can be effectively separated from sulfates such as sodium sulfate, ammonium sulfate or potassium sulfate in the vanadyl sulfate aqueous solution.

In the preparation method of the vanadium electrolyte of the present invention, the concentration of the second sulfuric acid aqueous solution is 3-6M, and the concentration of the second sulfuric acid aqueous solution is preferably 5M. In this way, the second sulfuric acid aqueous solution can effectively dissolve the vanadium oxyhydroxide, thereby forming the vanadium electrolyte.

〔this invention〕

1: Electrolyzer

2: electrode group

21: Anode electrode

21: Cathode electrode

3: Stirring piece

E: DC power supply

S1: slurry forming step

S2: Constant current electrolysis step

S3: precipitation step

S4: Redissolution step

[Fig. 1] A flowchart of a method for preparing a vanadium electrolyte solution according to an embodiment of the present invention.

[Fig. 2] The schematic diagram of the electrolysis device for implementing the preparation method of the vanadium electrolyte solution of the present embodiment.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments of the present invention are specifically cited below and described in detail with the accompanying drawings.

Please refer to Fig. 1, the method for preparing a vanadium electrolyte solution according to an embodiment of the present invention may roughly include a slurry forming step S1, a constant current electrolysis step S2, a precipitation step S3 and a back-dissolution step S4, by From the aforementioned four steps, workers can use vanadate as a raw material to generate a vanadium electrolyte.

Specifically, in the slurry forming step S1, workers first dissolve the vanadate in water to obtain a vanadate aqueous solution, and then mix the vanadate aqueous solution and a first sulfuric acid aqueous solution to obtain A mixed slurry is obtained. At this time, the vanadate will dissociate in water to form a vanadate ion (orthovanadate(V)anion, VO ₄ ^3- ), and the vanadate ion will react with the first sulfuric acid aqueous solution to form A dioxovanadium(V)cation, VO ₂ ⁺ ) is formed.

For example, the vanadate can be sodium vanadate (sodium orthovanadate, Na ₃ VO ₄ ), ammonium orthovanadate ((NH ₄ ) ₃ VO ₄ ) or potassium vanadate (potassium orthovanadate, K ₃ VO ₄ ), so, the dissociation constant (dissociation constant, K _D ) of these vanadates is relatively large, so they can be effectively dissociated in water to form the vanadate ions, and subjected to the first sulfuric acid aqueous solution, respectively according to the following chemical reactions formula one, formula two, formula three to form the dioxyvanadyl ion.

2 Na ₃ VO ₄ +5 H ₂ SO ₄ → VO ₂ ⁺ +3 Na ⁺ +2 SO ₄ ^2- +2 H ₂ O (Formula 1)

2( NH ₄ ) ₃ VO ₄ +5 H ₂ SO ₄ → VO ₂ ⁺ +3 Na ⁺ +2 SO ₄ ^2- +2 H ₂ O (Formula 2)

2 K ₃ VO ₄ +5 H ₂ SO ₄ → VO ₂ ⁺ +3 K ⁺ +2 SO ₄ ^2- +2 H ₂ O (Formula 3)

Preferably, the vanadate can be selected as cheap sodium vanadate (about 30% cheaper than vanadium pentoxide), so as to reduce the preparation cost of the vanadium electrolyte. In this embodiment, the vanadate aqueous solution is a 25-50 g/L sodium vanadate aqueous solution (that is, 25-50 g of sodium vanadate is dissolved in water to form an aqueous solution with a total volume of 1 L).

Again, in order to provide enough sulfuric acid to react with the vanadate, the first sulfuric acid aqueous solution may comprise 50-60% sulfuric acid and 40-50% water in weight percent (in other words, the weight percent of the first sulfuric acid aqueous solution The sub-concentration is between 50-60%, that is, every kilogram of the first sulfuric acid aqueous solution is formed by jointly preparing 500-600 grams of sulfuric acid and 400-500 grams of water).

In order to improve the subsequent electrolysis efficiency, the mixed slurry can include 30-70% of the vanadate aqueous solution and 30-70% of the first aqueous sulfuric acid solution by volume percentage, and preferably can include 30% by volume percentage. ~50% of the vanadate aqueous solution and 50~70% of the first sulfuric acid aqueous solution.

In the constant current electrolysis step S2, workers can set the electrolysis device as shown in Figure 2, and the electrolysis device can include an electrolytic cell 1 and an electrode group 2, and workers can accommodate the mixed slurry in In the electrolytic tank 1, the mixed slurry is continuously stirred by a stirring member 3 arranged in the electrolytic tank 1, so that the suspended solids in the mixed slurry can be evenly suspended in the mixed slurry without occurrence of Precipitation affects the efficiency of constant current electrolysis.

Please refer to Fig. 2 again, the electrode group 2 includes an anode electrode 21 and a cathode electrode 22, the anode electrode 21 and the cathode electrode 22 are respectively arranged in the mixed slurry, and the anode electrode 21 is connected to a DC power supply E, and the cathode electrode 22 is connected to the negative electrode of the DC electrode E. The materials of the anode electrode 21 and the cathode electrode 22 are not limited, it is only necessary to select a material that will not participate in the electrolysis reaction and will not be generated by the mixed slurry. For example, the anode electrode 21 Can be a titanium iridium plated electrode or a titanium rhodium plated electrode, and the cathode electrode 22 can be a lead electrode or a graphite electrode.

After the electrolysis device is set up, the worker can turn on the DC power supply E to perform constant current electrolysis, so that the vanadyl (IV) anion is reduced to form a vanadyl (IV) anion , VO ²⁺ ).

At this time, the half equation of the electrolysis reaction at the anode electrode 21 is shown in Equation 4 below.

The half-reaction formula of the electrolysis reaction at the cathode electrode 22 is shown in the following formula 5.

The cell equation of the electrolysis reaction is shown in Equation 6 below.

Then, after a predetermined electrolysis time, the worker can turn off the DC power supply E, at this time, the vanadyl ions in the electrolytic cell 1 can form vanadyl (IV) sulfate (vanadyl (IV) ) together with the sulfate ions. sulfate, VOSO ₄ ), and then workers can collect a vanadyl sulfate aqueous solution in the electrolytic cell 1 . According to Faraday's law of electrolysis, in the constant current electrolysis reaction, the magnitude of the current used will be inversely proportional to the required electrolysis time, so workers can adjust the constant current electrolysis reaction according to their needs. Current size and electrolysis time, for example, workers can choose to conduct constant current electrolysis with a current of 10~20A for 2~8 hours, and it is better to conduct constant current electrolysis with a current of 15~20A for 4~8 hours.

It should be noted that, before the constant current electrolysis, there are cations formed by the dissociation of the vanadate in the mixed slurry (for example, sodium ions (sodium cation, Na ⁺ ) formed by the dissociation of sodium vanadate, The ammonium cation (NH ₄ ⁺ ) formed by the dissociation of ammonium vanadate or the potassium ion (potassium cation, K ⁺ ) formed by the dissociation of potassium vanadate], after the DC power supply E is turned off, exists in the electrolytic The vanadyl ion and the sulfate ion in the tank 1 will also react with the cation (such as , the sodium ions, the ammonium ions or the potassium ions) react, and thus the obtained aqueous solution of vanadyl sulfate contains, in addition to vanadyl sulfate, sodium sulfate (sodium sulfate, Na ₂ SO ₄ ), ammonium sulfate (NH ₄ ) ₂ SO ₄ ) or potassium sulfate (potassium sulfate, K ₂ SO ₄ ) and other sulfates.

VO ²⁺ +2 Na ⁺ +2 SO ₄ ^2- → VOSO ₄ + Na ₂ SO ₄ (Formula 7)

VO ²⁺ +2 NH ₄ ⁺ +2 SO ₄ ^2- → VOSO ₄ +( NH ₄ ) ₂ SO ₄ (Formula 8)

VO ²⁺ +2 K ⁺ +2 SO ₄ ^2- → VOSO ₄ + K ₂ SO ₄ (Formula 9)

In order to remove sulfates other than vanadyl sulfate in the vanadyl sulfate aqueous solution, in the precipitation step S3, workers can add a lye to the vanadyl sulfate aqueous solution to form a water-insoluble hydroxide Vanadium oxydihydroxide (VO(OH) ₂ ) precipitates. For example, the lye can be a sodium hydroxide (NaOH) aqueous solution, an ammonia solution (NH ₃ ‧H ₂ O) or a potassium hydroxide (potassium hydroxide, KOH) aqueous solution, so sulfuric acid Vanadyl can be affected by these lyes, and form water-insoluble vanadyl hydroxide according to the following chemical reaction formulas 10, 11 and 12 respectively.

VOSO ₄ +2 NaOH → VO ( OH ) ₂ + Na ₂ SO ₄ (Formula 10)

VOSO ₄ +2 NH ₃ ‧H ₂ O → VO ( OH ) ₂ +( NH ₄ ) ₂ SO ₄ (Formula 11)

VOSO ₄ +2 KOH → VO ( OH ) ₂ + K ₂ SO ₄ (Formula 12)

Preferably, workers can adjust the pH value of the mixed solution comprising the vanadyl sulfate aqueous solution and the lye to 4-6 by adding the lye, so that sufficient hydroxide ions can be provided (hydroxide anion, OH ^- ), promoting vanadyl sulfate can quickly form vanadyl hydroxide. In this embodiment, the pH value of the mixed solution comprising the vanadyl sulfate aqueous solution and the alkaline solution is adjusted to 5.

Next, in the back-dissolving step S4, workers can separate the water-insoluble vanadium hydroxide by means of filtration, etc., and then dissolve the obtained vanadium hydroxide in a second sulfuric acid aqueous solution to obtain The vanadium electrolyte.

VO ( OH ) ₂ + H ₂ SO ₄ → VOSO ₄ +2 H ₂ O (Formula 13)

In order to provide enough sulfuric acid to dissolve vanadyl hydroxide, the concentration of the second sulfuric acid aqueous solution may be 3-6M. In this embodiment, the concentration of the second sulfuric acid aqueous solution is 5M.

In order to confirm that the vanadium electrolyte can be prepared according to the preparation method of the vanadium electrolyte of the present embodiment, the following tests were carried out:

(A) Mixing volume ratio of mixed slurry

This test system takes the sodium vanadate aqueous solution that concentration is 35g/L as this vanadate aqueous solution, and gets the sulfuric acid aqueous solution that is 50% by weight percent concentration as this first sulfuric acid aqueous solution (comprising 50% sulfuric acid by weight percent) and 50% water), after mixing the vanadate aqueous solution and the first sulfuric acid aqueous solution according to the mixing volume ratio shown in the first table, the mixed slurry of each group was obtained. Then, get the mixed slurry of 1000g, be placed in the electrolyzer 1 of the electrolytic device as shown in Fig. A current of 15A was used for constant-current electrolysis for 4 hours (the voltage was 4V), and the obtained aqueous solution of vanadyl sulfate was subjected to redox titration detection to convert tetravalent vanadium ions (VO ²⁺ ) and pentavalent vanadium in the aqueous solution of vanadyl sulfate. Molar percentage of ions (VO ₂ ⁺ ).

Please refer to Table 1, the mixed slurry obtained by mixing the sodium vanadate aqueous solution and the first sulfuric acid aqueous solution at a mixing volume ratio of 1:0.5~1:2 can effectively dissolve the Pentavalent vanadium ions (VO ₂ ⁺ ) are reduced to form tetravalent vanadium ions (VO ²⁺ ), and when the mixed volume ratio reaches 1:1 or more, the tetravalent vanadium ions can account for the total amount of vanadium ions (including the pentavalent Vanadium ions and the mole percentage of the tetravalent vanadium ions) is more than 99% (groups A2~A4).

(B) Current of constant current electrolysis

This test system takes the sodium vanadate aqueous solution that concentration is 35g/L as this vanadate aqueous solution, and gets the sulfuric acid aqueous solution that is 50% by weight percent concentration as this first sulfuric acid aqueous solution (comprising 50% sulfuric acid by weight percent) and 50% water), after mixing the vanadate aqueous solution and the first sulfuric acid aqueous solution according to the mixing volume ratio of 1:1, the mixed slurry of each group was obtained. Then, get the mixed slurry of 1000g, be placed in the electrolyzer 1 of the electrolytic device as shown in Fig. Carry out constant current electrolysis 4 hours (voltage is 4V) as the electric current shown in the 2nd table, the vanadyl sulfate aqueous solution obtained is carried out redox titration detection, to convert ^tetravalent vanadium ion (VO in this vanadyl sulfate aqueous solution ) to the molar percentage of pentavalent vanadium ions (VO ₂ ⁺ ).

Please refer to Table 2, after constant current electrolysis with a current between 5~20A can effectively reduce pentavalent vanadium ions (VO ₂ ⁺ ) to form tetravalent vanadium ions (VO ²⁺ ), and when used When the current is above 15A, the tetravalent vanadium ions can account for more than 99% of the molar percentage of the total amount of vanadium ions (including the pentavalent vanadium ions and the tetravalent vanadium ions) (groups B3-B4).

(C) Time for constant current electrolysis

This test system takes the sodium vanadate aqueous solution that concentration is 35g/L as this vanadate aqueous solution, and gets the sulfuric acid aqueous solution that is 50% by weight percent concentration as this first sulfuric acid aqueous solution (comprising 50% sulfuric acid by weight percent) and 50% water), after mixing the vanadate aqueous solution and the first sulfuric acid aqueous solution according to the mixing volume ratio of 1:1, the mixed slurry of each group was obtained. Then, get the mixed slurry of 1000g, be placed in the electrolyzer 1 of the electrolytic device as shown in Fig. The electric current of 15A carries out constant-current electrolysis (voltage is 4V), and electrolysis time is as shown in the 3rd table, and the obtained vanadyl sulfate aqueous solution is carried out oxidation-reduction titration detection, to convert tetravalent vanadium ion (VO) in this vanadyl sulfate aqueous solution ²⁺ ) to the molar percentage of pentavalent vanadium ions (VO ₂ ⁺ ).

Please refer to Table 3, after 2~8 hours of constant current electrolysis, pentavalent vanadium ions (VO ₂ ⁺ ) can be effectively reduced to tetravalent vanadium ions (VO ²⁺ ), and when the constant current electrolysis time reaches 4 Hours, the tetravalent vanadium ions can account for more than 99% of the molar percentage of the total amount of vanadium ions (comprising the pentavalent vanadium ions and the tetravalent vanadium ions) (groups C2-C4).

(D) Selection of anode electrodes

This test system takes the sodium vanadate aqueous solution that concentration is 35g/L as this vanadate aqueous solution, and gets the sulfuric acid aqueous solution that is 50% by weight percent concentration as this first sulfuric acid aqueous solution (comprising 50% sulfuric acid by weight percent) and 50% water), after mixing the vanadate aqueous solution and the first sulfuric acid aqueous solution according to the mixing volume ratio of 1:1, the mixed slurry of each group was obtained. Then, take 1000g of the mixed slurry, place it in the electrolytic cell 1 of the electrolysis device as shown in Fig. 2, use the electrode as shown in Table 4 as the anode electrode 21, and use the lead electrode as the cathode electrode 22. Carry out constant current electrolysis with a current of 15A for 4 hours (the voltage is 4V), and perform redox titration detection on the obtained vanadyl sulfate aqueous solution to convert the tetravalent vanadium ion (VO ²⁺ ) in the vanadyl sulfate aqueous solution. Molar percentage of pentavalent vanadium ions (VO ₂ ⁺ ).

Please refer to Table 4, whether the titanium iridium-plated electrode or the titanium rhodium-plated electrode is used as the anode electrode 21, the pentavalent vanadium ions (VO ₂ ⁺ ) can be effectively reduced to form tetravalent vanadium ions (VO ^{2 +} ), and the tetravalent vanadium ions can account for more than 99% of the molar percentage of the total amount of vanadium ions (including the pentavalent vanadium ions and the tetravalent vanadium ions) (groups D1 and D2).

(E) Selection of cathode electrode

This test system takes the sodium vanadate aqueous solution that concentration is 35g/L as this vanadate aqueous solution, and gets the sulfuric acid aqueous solution that is 50% by weight percent concentration as this first sulfuric acid aqueous solution (comprising 50% sulfuric acid by weight percent) and 50% water), after mixing the vanadate aqueous solution and the first sulfuric acid aqueous solution according to the mixing volume ratio of 1:1, the mixed slurry of each group was obtained. Then, get the mixed slurry of 1000g, be placed in the electrolyzer 1 of the electrolysis device as shown in Fig. Cathode electrode 22, carry out constant current electrolysis 4 hours (voltage is 4V) with the electric current of 15A, the vanadyl sulfate aqueous solution obtained is carried out redox titration detection, to convert the tetravalent vanadium ion (VO in this ^vanadyl sulfate aqueous solution ) to the molar percentage of pentavalent vanadium ions (VO ₂ ⁺ ).

Please refer to Table 5, whether the lead electrode or the graphite electrode is used as the cathode electrode 22, the pentavalent vanadium ions (VO ₂ ⁺ ) can be effectively reduced to form tetravalent vanadium ions (VO ²⁺ ), and The tetravalent vanadium ions can account for more than 99% of the molar percentage of the total amount of vanadium ions (including the pentavalent vanadium ions and the tetravalent vanadium ions) (groups E1 and E2).

(F) Output of vanadium electrolyte

This test is to get the vanadyl sulfate aqueous solution of the aforementioned E2 group and add the lye (aqueous sodium hydroxide solution that is 10 to 20% by weight) in the vanadyl sulfate aqueous solution, so as to contain the vanadyl sulfate aqueous solution and After the pH value of the mixed solution of the lye is adjusted to 5, water-insoluble vanadium hydroxide is formed, and after the vanadium hydroxide is obtained by means of filtration, the vanadium hydroxide is dissolved in the second sulfuric acid aqueous solution (concentration is 5M sulfuric acid aqueous solution), and finally the obtained vanadium electrolyte was subjected to redox titration detection to convert the molar percentage of tetravalent vanadium ions (VO ²⁺ ) and pentavalent vanadium ions (VO ₂ ⁺ ) in the vanadium electrolyte , and detect the vanadium loss rate of the vanadium electrolyte.

Please refer to Table 6, the vanadium electrolyte solution obtained through the precipitation step S3 and the back-dissolution step S4 still contains more than 99% of the molar percentage of tetravalent vanadium ions (VO ²⁺ ), and the vanadium loss rate Only 1.8%, showing that the product prepared by the preparation method of the vanadium electrolyte in this embodiment can indeed be used as a vanadium electrolyte.

In summary, the preparation method of the vanadium electrolyte of the present invention can reduce the trivalent vanadium ions (VO 2 + ) in the mixed slurry to form ^tetravalent vanadium ions (VO ₂ ⁺ ) through the constant current electrolysis step S2 ⁺ ), and then through the precipitation step S3 and the back-dissolution step S4, the vanadium sulfate containing the tetravalent vanadium ion can be separated from sulfates such as sodium sulfate, ammonium sulfate or potassium sulfate, and then obtain the vanadium electrolyte, It is the effect of the present invention.

Moreover, through the slurry forming step S1, workers can choose low-cost vanadate as a raw material, and after reacting with the first aqueous sulfuric acid solution, they can obtain trivalent vanadate that can carry out the constant current electrolysis step S2 Vanadium ions (VO ₂ ⁺ ), and then preparing the vanadium electrolyte, can achieve the effect of reducing the production cost of the vanadium electrolyte.

Although the present invention has been disclosed by using the above-mentioned preferred embodiments, it is not intended to limit the present invention. It is still within the scope of this invention for anyone skilled in the art to make various changes and modifications relative to the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall include all changes within the meaning and equivalent scope described in the appended scope of application.

S1: slurry forming step

S2: Constant current electrolysis step

S3: precipitation step

S4: Redissolution step

Claims (15)

A method for preparing a vanadium electrolyte, comprising: mixing a vanadate aqueous solution and a first sulfuric acid aqueous solution to obtain a mixed slurry, the vanadate aqueous solution being a 25-50 g/L sodium vanadate aqueous solution, and the mixed slurry It contains a vanadyl ion and a sulfate ion; the mixed slurry is subjected to constant current electrolysis, so that the vanadyl ion is reduced to form a vanadyl ion, and together with the sulfate ion, vanadyl sulfate is formed , to form a vanadyl sulfate aqueous solution; add a lye to the vanadyl sulfate aqueous solution, so that the vanadyl sulfate forms water-insoluble vanadyl hydroxide; and dissolve the vanadyl hydroxide obtained by filtration in a second sulfuric acid aqueous solution to obtain a vanadium electrolyte. The method for preparing a vanadium electrolyte according to claim 1, wherein the first sulfuric acid aqueous solution comprises 50-60% sulfuric acid and 40-50% water by weight percentage. The method for preparing a vanadium electrolyte according to claim 1, wherein the mixed slurry contains 30-70% of the vanadate aqueous solution and 30-70% of the first sulfuric acid aqueous solution in volume percentage. The method for preparing a vanadium electrolyte according to claim 3, wherein the mixed slurry contains 30-50% of the vanadate aqueous solution and 50-70% of the first sulfuric acid aqueous solution in volume percentage. Such as the preparation method of the vanadium electrolyte of claim item 1, the mixed slurry is placed in an electrolytic cell for constant current electrolysis. The preparation method of vanadium electrolyte as claimed in item 5, wherein, an anode electrode is provided in the electrolytic cell, and the anode electrode is a titanium iridium-plated electrode or a titanium rhodium-plated electrode. The preparation method of vanadium electrolyte as claimed in item 5, wherein a cathode electrode is provided in the electrolytic cell, and the cathode electrode is a lead electrode or a graphite electrode. Such as the preparation method of the vanadium electrolyte in claim item 1, wherein the constant current electrolysis is performed with a current of 10-20A for 2-8 hours to form the vanadyl sulfate aqueous solution. Such as the preparation method of the vanadium electrolyte of claim item 8, wherein the constant current electrolysis is performed with a current of 15-20A. Such as the preparation method of the vanadium electrolyte of claim item 8, wherein the constant current electrolysis is carried out for 4 to 8 hours. The preparation method of the vanadium electrolytic solution as claimed in item 1, wherein, the alkaline solution is added to the vanadyl sulfate aqueous solution to adjust the pH value of the mixed solution comprising the vanadyl sulfate aqueous solution and the alkaline solution to 4~6, To make vanadyl sulfate form vanadyl hydroxide. The preparation method of the vanadium electrolyte as claimed in item 11, wherein, the alkaline solution is added to the vanadyl sulfate aqueous solution to adjust the pH value of the mixed solution comprising the vanadyl sulfate aqueous solution and the alkaline solution to 5, so that Vanadyl sulfate forms vanadyl hydroxide. The preparation method of the vanadium electrolyte solution as claimed in item 11, wherein the lye is an aqueous sodium hydroxide solution, an aqueous ammonia solution or an aqueous potassium hydroxide solution. The method for preparing the vanadium electrolyte as claimed in item 1, wherein the concentration of the second sulfuric acid aqueous solution is 3-6M. The method for preparing the vanadium electrolyte according to claim 14, wherein the concentration of the second sulfuric acid aqueous solution is 5M.

Images